1. Technical Field
The present invention relates generally to sliding door mechanisms for automobiles, and more specifically to upper track roller mechanisms for such doors.
2. Description of the Prior Art
In the fabrication of certain types of automotive vehicles, such as passenger vans, it is known to provide access to rear portions of the vehicle interior compartment by use of a sliding door mechanism. In the typical sliding door mechanism, the door, in its closed position, is flush with the side of the vehicle in a latched position. Moving from the latch position, the door is moved outward with respect to the side of the vehicle and then slid rearwardly to an open position. The outward and rearward motion of the sliding door is controlled by roller mechanisms engaged between the door and the vehicle body at vertically spaced surface of the door. In some vehicles, an upper track roller mechanism is provided at top of the door aperture, which employs a curved track mechanism which receives a roller rotatable about a vertical axis. The roller is typically mounted on a linkage which is pivotally connected to the door. U.S. Pat. No. 4,569,553 is exemplary of such a design.
Because of dimensional variances in building a high volume of such vehicles, controlling the vertical position of the track roller during its full range of movement in operation of the door is very difficult to accomplish. It is of course desirable that the roller not rubbingly engage either the top nor bottom surface of the track. Such contact causes undesirable wear and noise in the operation of the sliding door. To control such vertical excursions, the mechanism disclosed in U.S. Pat. No. '553 provides a guide lip on the track and a pair of fingers adjacent the roller to limit vertical movement. While effective for its purpose, this design necessitates the use of auxiliary structure which is considered uneconomical to manufacture in some applications. It also suffers from the disadvantage of providing the vertical guide structure which employs a guide lip at a position depending below the track structure defined by the primary function of the track roller, that is, a roller and track structure of increased height is employed in order to effect the vertical guiding function.